TUNNELING THROUGH A DOUBLE-BARRIER STRUCTURE IRRADIATED BY INFRARED RADIATION

We have calculated the transmission probability of electrons through an irradiated GaAs double-barrier structure. The frequency of the radiation is in the infrared range. We describe the tunneling by a transfer Hamiltonian with two different resonant levels in the quantum well. The parameters entering the Hamiltonian are calculated from a realistic potential. The interaction with the electromagnetic radiation is only included within the quantum-well region of the double-barrier structure. Our method of solution is based on a Green's-function treatment of the electrons in the quantum well, by which we are able to treat multiphoton processes to high order with very little calculational effort. Our results show that relatively weak infrared radiation can cause considerable changes in the transmission probability of an electron. The dynamic Stark effect introduces shifts of the positions of the resonant levels. Moreover, the radiation tends to suppress the transmission through the lower resonant level due to the mixing of the two levels that the radiation causes. We also find that photon emission is a more efficient process in assisting resonant tunneling than is photon absorption. The presence of radiation typically leads to a decrease of the peak current through the structure while the valley current can increase.